Warts are benign tumors that commonly involve skin and less frequently affect other epithelial tissues. These lesions are induced by papillomaviruses which are deoxyribonucleic acid (DNA)-containing viruses. The approach to treatment of warts depends on the age of the patient, the extent and duration of lesions and the patient's immunological status. Common therapy has been cryotherapy, using caustics and acids such as salicylic acid, lactic acid, trichloracetic acid or retinoic acid. Unfortunately, many warts resist such treatment, especially in organ transplant patients.
Keratoacanthoma is a common keratinizing cutaneous squamous neoplasm characterized by rapid and prolific growth sometimes followed by spontaneous involution, classically occurring on the sun-exposed skin of elderly light skinned individuals. There are several methods of treating keratoacanthomas. Surgical excision and injectable intralesional 5-fluorouracil have been used to remove lesions, but scarring occurs from surgery and necrosis of tissue occurs. 5-Fluorouracil has been used for solitary, multiple and large lesions. This treatment requires painful injections and needs to be complete to be effective. Corticosteroids have been used with variable success.
U.S. Pat. No. 5,089,509 to Chandraratna, which is herein incorporated by reference, discloses the preparation and use of tazarotene in the treatment of immunological disorders such as lupus, epithelial cancers and psoriasis.